TypeError: 'unicode' does not have the buffer interface

[clebio]

I'm attempting to use this repo for the first time as I work through the book. I run into an error when trying to log in, after creating a user. I've tried going through the new user registration flow within the app (though I don't have gmail configured) and also tried adding a user as the book describes in chapter eight:

$ ./manage.py shell
>>> u = User(email='john@example.com', username='john', password='cat')
>>> db.session.add(u)
>>> db.session.commit()

From the terminal, the error shows as:

 $ ./manage.py runserver
 * Running on http://127.0.0.1:5000/
 * Restarting with reloader
127.0.0.1 - - [04/Jul/2014 19:08:05] "GET / HTTP/1.1" 200 -
127.0.0.1 - - [04/Jul/2014 19:08:06] "GET /auth/login HTTP/1.1" 200 -
127.0.0.1 - - [04/Jul/2014 19:08:17] "POST /auth/login HTTP/1.1" 500 -
Traceback (most recent call last):
  File "/home/caleb/.virtualenvs/flasky/lib/python2.7/site-packages/flask/app.py", line 1836, in __call__
    return self.wsgi_app(environ, start_response)
  File "/home/caleb/.virtualenvs/flasky/lib/python2.7/site-packages/flask/app.py", line 1820, in wsgi_app
    response = self.make_response(self.handle_exception(e))
  File "/home/caleb/.virtualenvs/flasky/lib/python2.7/site-packages/flask/app.py", line 1403, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "/home/caleb/.virtualenvs/flasky/lib/python2.7/site-packages/flask/app.py", line 1817, in wsgi_app
    response = self.full_dispatch_request()
  File "/home/caleb/.virtualenvs/flasky/lib/python2.7/site-packages/flask/app.py", line 1477, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/home/caleb/.virtualenvs/flasky/lib/python2.7/site-packages/flask/app.py", line 1381, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/home/caleb/.virtualenvs/flasky/lib/python2.7/site-packages/flask/app.py", line 1475, in full_dispatch_request
    rv = self.dispatch_request()
  File "/home/caleb/.virtualenvs/flasky/lib/python2.7/site-packages/flask/app.py", line 1461, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/home/caleb/dev/flasky/app/auth/views.py", line 13, in login
    if user is not None and user.verify_password(form.password.data):
  File "/home/caleb/dev/flasky/app/models.py", line 33, in verify_password
    return check_password_hash(self.password_hash, password)
  File "/home/caleb/.virtualenvs/flasky/lib/python2.7/site-packages/werkzeug/security.py", line 224, in check_password_hash
    return safe_str_cmp(_hash_internal(method, salt, password)[0], hashval)
  File "/home/caleb/.virtualenvs/flasky/lib/python2.7/site-packages/werkzeug/security.py", line 117, in safe_str_cmp
    return _builtin_safe_str_cmp(a, b)
TypeError: 'unicode' does not have the buffer interface

The full error on the app itself is:

TypeError
TypeError: 'unicode' does not have the buffer interface

Traceback (most recent call last)
File "/home/caleb/.virtualenvs/flasky/lib/python2.7/site-packages/flask/app.py", line 1836, in __call__
return self.wsgi_app(environ, start_response)
File "/home/caleb/.virtualenvs/flasky/lib/python2.7/site-packages/flask/app.py", line 1820, in wsgi_app
response = self.make_response(self.handle_exception(e))
File "/home/caleb/.virtualenvs/flasky/lib/python2.7/site-packages/flask/app.py", line 1403, in handle_exception
reraise(exc_type, exc_value, tb)
File "/home/caleb/.virtualenvs/flasky/lib/python2.7/site-packages/flask/app.py", line 1817, in wsgi_app
response = self.full_dispatch_request()
File "/home/caleb/.virtualenvs/flasky/lib/python2.7/site-packages/flask/app.py", line 1477, in full_dispatch_request
rv = self.handle_user_exception(e)
File "/home/caleb/.virtualenvs/flasky/lib/python2.7/site-packages/flask/app.py", line 1381, in handle_user_exception
reraise(exc_type, exc_value, tb)
File "/home/caleb/.virtualenvs/flasky/lib/python2.7/site-packages/flask/app.py", line 1475, in full_dispatch_request
rv = self.dispatch_request()
File "/home/caleb/.virtualenvs/flasky/lib/python2.7/site-packages/flask/app.py", line 1461, in dispatch_request
return self.view_functions[rule.endpoint](**req.view_args)
File "/home/caleb/dev/flasky/app/auth/views.py", line 13, in login
if user is not None and user.verify_password(form.password.data):
File "/home/caleb/dev/flasky/app/models.py", line 33, in verify_password
return check_password_hash(self.password_hash, password)
File "/home/caleb/.virtualenvs/flasky/lib/python2.7/site-packages/werkzeug/security.py", line 224, in check_password_hash
return safe_str_cmp(_hash_internal(method, salt, password)[0], hashval)
File "/home/caleb/.virtualenvs/flasky/lib/python2.7/site-packages/werkzeug/security.py", line 117, in safe_str_cmp
return _builtin_safe_str_cmp(a, b)
TypeError: 'unicode' does not have the buffer interface
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[miguelgrinberg]

Looks like this is an issue in Werkzeug when you use Python 2.7.7. Here is the bug report. I think the easiest workaround is to downgrade to Python 2.7.6.

[clebio]

Ok, thanks for the quick response! I couldn't tell whether I'd maybe left a step out (db init, migrate, runserver, etc.) that was necessary.

Understanding the bug you linked to, I was able to resolve this just by modifying my python 2.7 virtualenv:

cdsitepackages
vim werkzeug/security.py

Searched for _builtin_safe_str_cmp and add bytes as described. That fixed it for me.

My user was still unconfirmed, but I resolved that by just setting 'confirmed' when adding the user at the manage.py shell:

u = User(email='biff@example.com', username='biff', password='cat', confirmed=True)

[miguelgrinberg]

Great, glad you figured out a workaround. Note that in this application all users are created unconfirmed. Each user receives an email with a confirmation link, the state changes to confirmed when the link is clicked.

[jwieland]

Another way to solve the issues is upgrading Werkzeug from 0.9.4 to 0.9.6

[miguelgrinberg]

Yes, looks like they released a fixed for this bug now, but note it is 0.9.5 the version that includes this fix.

[hugoeiji]

I updated to 0.9.6 and now the error is also gone :)